Question

Predict in which of the following, entropy

increases/decreases :

(i) A liquid crystallizes into a solid.

(ii) Temperature of a crystalline solid is

raised from 0 K to 115 K.

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Answer 1

$\huge\underline{\underline\mathtt{Answer:-}}$

Solution

(i) After freezing, the molecules attain anordered state and therefore, entropydecreases.

(ii) At 0 K, the contituent particles arestatic and entropy is minimum. Iftemperature is raised to 115 K, thesebegin to move and oscillate about

their equilibrium positions in thelattice and system becomes moredisordered, therefore entropyincreases.

(iii) Reactant, NaHCO3 is a solid and ithas low entropy. Among productsthere are one solid and two gases.Therefore, the products represent a

condition of higher entropy.

(iv) Here one molecule gives two atomsi.e., number of particles increasesleading to more disordered state.Two moles of H atoms have higherentropy than one mole of dihydrogen

molecule.

Answer 2

Answer:

(b) At 0K, the constituent particles are static and entropy is minimum. If temperature is raised to 115K, these begin to move and oscillate about their equilibrium positions in the lattice and system becomes more disordered, hence entropy increases.